First person pronouns are a rhetorical strategy which allows researchers to perform different discourse functions in the text, through which they construct a convincing argument that persuades readers of the validity and novelty of their claims and of their own competence. In this paper I explore how Spanish EFL Engineering students use first person plural pronouns in multi-authored report writing. The paper examines the discourse functions of the pronoun "we" in a corpus of 55 reports written by Spanish students. The analysis shows that these students fail to understand how expert writers use these pronouns to construct their authorial identities as knowledgeable members of the community. Students are unaware of the conventionalised use of phraseological patterns involving "we" to perform specific functions in academic genres. The results clearly suggest the need for an approach to academic writing in higher education which combines genre analysis, expert corpora and learner corpora. (Contains 4 tables.)